We are now ready to add web support to our working sensor, which we prepared in the previous chapter, and publish its data using the HTTP protocol. The following are the three basic strategies that one can use when publishing data using HTTP:
In the first strategy the sensor is a client who publishes information to a server on the Internet. The server acts as a broker and informs the interested parties about sensor values. This pattern is called publish/subscribe, and it will be discussed later in this book. It has the advantage of simplifying handling events, but it makes it more difficult to get momentary values. Sensors can also be placed behind firewalls, as long as the server is publically available on the Internet.
Another way is to let all entities in the network be both clients and servers, depending on what they need to do. This pattern will be discussed in Chapter 3, The UPnP Protocol. This reduces latency in communication, but requires all participants...